Granted, in “Soylent Green,” that line conveyed a decidedly shocking and unsavory meaning. But when it comes to documentaries, both the blessing and the curse of the form is that the subjects themselves — rather than the formal, aesthetic or technical sophistication of the narrative — are what make or break the film.

A core sample of movies with strong local ties proves the rule. Although none of the films takes many narrative risks — hewing to the straightforward, un-narrated format favored by documentary filmmakers these days — each introduces viewers to unforgettable characters whose perseverance and clear-eyed focus would spark envy in any Hollywood screenwriter trying to come up with a compelling protagonist.

Take Tony Geraci, the star of Richard Chisolm’s “Cafeteria Man.” In 2008, Geraci arrived in Baltimore to take over the city’s school lunch program, promising healthier meals for the system’s 85,000 kids. The film traces Geraci’s two-year fight to start a farm and a central kitchen, teach underserved children how to cook high-quality meals and fight a bureaucracy mired in pre-packaged thinking. But, contrary to its title, “Cafeteria Man” comes most alive when the kids are on screen, starting gardens, learning how to cook and advocating for their nutritional futures in Congress.

Geraci, who left his post a year ago, emerges as a sympathetic but frustrating would-be hero, brimming with bravado and vision but lacking the patience and political skills necessary to bring them to fruition. A perhaps more worthy subject might have been Alice Sheehan, or “Cafeteria Girl,” who despite the fecklessness of grown-ups around her emerges as a determined avatar of structural change.

The Baltimore school system provides a different kind of backdrop for “The Learning,” about four teachers from the Philippines who arrive to teach in the city’s public schools. Ramona Diaz’s illuminating, absorbing documentary doesn’t delve into the political or legal implications of the little-known guest-worker program in American education. Instead, the filmmaker concentrates on Dorotea, Grace, Rhea and Angel, who can earn up to 25 times as much here as they do at home, where their families impatiently wait for their regular remittances.

Suffering culture shock (“It’s all bricks,” one teacher mutters, looking at Baltimore’s “Wire”-worthy mean streets), chaotic classrooms and intense pressure from their families to send back money, Diaz’s heroines become the unforgettable faces of a story all the more shocking for being so little-known. (The film’s most gratifying scenes are when the small, meek Angel finally stands up to her family members back home, giving them a schooling in filial responsibility they’ll never forget.)

Viewers are privy to sometimes uncomfortably intimate glimpses of the four heroines’ lives in “The Learning,” but they’re kept at arm’s length in “Being Elmo: A Puppeteer’s Journey,” about Baltimore-bred puppeteer Kevin Clash. Still, it may come as a shock for “Sesame Street” fans to learn that the persona behind little red, cuddly Elmo is a tall, 50-year-old African American man. “Being Elmo” rarely delves deeper than the average resume, but Constance Marks’s film nonetheless tells the inspiring story of a gifted artist who, despite being teased for playing with dolls as a kid, bravely took up his mom’s needle and thread and just kept on sewing.

Clash’s clear-eyed determination and quiet focus find their analogs further south on Interstate 95, where local swimming champions Bradford and John Tatum have long trained for the Senior Olympics. “Age of Champions” chronicles the brothers’ training regime in 2009, when, at ages 88 and 90, respectively, they swam for the gold medal in California (Post readers may remember the outcome, but no spoilers here).

The Tatum brothers, who grew up in Washington during the segregation era and separate swimming pools, recall swimming in the Potomac River and the Lincoln Memorial reflecting pool “and sometimes the Georgetown Canal.” When filmmaker Chris Rufo catches up with them, the lithe, soft-spoken men are each seeking to overcome his own obstacle: Bradford, the colon cancer he’s being treated for over the course of the film; John, the simple depredations of time.

As a profile of perseverance and discipline, “Age of Champions” is infectiously inspiring — which is, no doubt, exactly what the National Senior Games Association had in mind when they co-sponsored it. But for profiles in pure courage, it doesn’t get more sobering than two other locally set films: “Semper Fi: Always Faithful,” about a Marine veteran’s efforts to expose the worst case of water contamination in history at North Carolina’s Camp Lejeune, and “The Loving Story,” about Mildred and Richard Loving, whose interracial marriage in Virginia in 1958 broke and ultimately changed miscegenation laws.

In fact, Marine Corps Master Sgt. Jerry Ensminger, the protagonist of “Semper Fi,” would probably have a lot in common with Richard Loving, whose crew cut and literally red neck made him an unlikely civil-rights-era hero. When Ensminger’s daughter Janey died of leukemia in the 1970s, he was plagued with questions until he learned that Lejeune’s water supply had been poisoned with leaked fuel and chemicals for 30 years; for Loving’s part, just weeks after he married Mildred — who was half-black, half-Rappahannock Indian — they were arrested, jailed and ordered not to return to Virginia.

Ensminger’s quest for justice ultimately ends up in Washington, as does the Lovings’ story. But as effective as both films are as legal thrillers, ultimately they hinge on the implacable moral authority of the characters who drive them. Jerry Ensminger isn’t an environmental or public health crusader as much as a grieving father. Richard and Mildred Loving aren’t civil rights activists, but a young married couple who want to bring up their three children in the rolling Virginia farmland where they had grown up.

Shy and reticent, Richard and Mildred Loving evince the quiet focus of the Tatum brothers, the women of “The Learning” and the kids of “Cafeteria Man,” albeit in a struggle with much higher stakes. Film fans may flock to Silverdocs for the movies, but they’ll remember it for the people — whose dramatic stories, harrowing emotional arcs and occasionally superhuman feats of psychic and physical strength possess the added frisson of being true.

The AFI-Discovery Channel Silverdocs Documentary Festival

opens June 20 with a screening of “The Swell Season,” about the musicians Glen Hansard and Marketa Irglova. The festival continues through June 28 at AFI Silver Theatre and Cultural Center, 8633 Colesville Rd., Silver Spring, Md.